This invention relates to a catheter with an injection needle for infusing therapeutic or diagnostic agents into the tissue of organs, and more particularly to a catheter having a spring-loaded handle for controlled extension of an injection needle.
Targeted delivery of therapeutic or diagnostic agents, such as occurs in gene therapy, is very desirable but often presents a difficult challenge. A potential benefit of targeted delivery is that there is an increased efficiency obtained by the precise placement of the therapeutic agent. There are several problems to his procedure which must be overcome in order to obtain satisfactory results from such therapy, such as the problems of obtaining access to the delivery site, transporting the therapeutic agent to the desired site, injecting the therapeutic agent at the proper depth within the organ tissue, steering the distal end of the catheter to a desired location within the organ prior to infusing the agent, and positioning the distal tip of the catheter at precisely the same location where prior measurements have indicated that the drug should be infused. It is also important to for a physician to be able to monitor the position of the infusion needle with respect to the wall of the organ. In the case of an organ, such as the heart, in which the walls are in constant motion, the activity of positioning and monitoring the position of the distal tip of the catheter, or infusion needle, becomes especially difficult.
U.S. Pat. No. 3,598,119 discloses a medical device for injecting drugs in which the injection needle is guided through an inner lumen of a catheter for insertion of the needle under skin tissue. A bladder at the distal end of the catheter may be inflated through another lumen for holding the point of the needle point in a fixed position beneath the skin.
U.S. Pat. No. 4,578,061 discloses a catheter for injecting a liquid into a vein, or artery, through an injection needle which is longitudinally movable beyond the distal end of the catheter. A dual chamber system is utilized within the catheter tip to provide for movement of a plunger to extend the injection needle and also to allow for a plunger to be used to apply a predetermined dose of medication through the injection needle.
U.S. Pat. No. 4,578,061 discloses an injection catheter having a longitudinal movable needle which may be moved through a lumen in order to extend out of the side wall of the catheter for injecting a liquid into a blood vessel. The needle is normally retracted into the device so that the needle will not penetrate tissue as the device is moved through a body duct. Thereafter, the needle is moved out of the side of the catheter into a vessel wall in order to infuse a liquid into the wall of a vessel.
U.S. Pat. No. 5,244,460 is directed toward a method for improving blood flow to the heart. More particularly this patent is directed toward a medical procedure for improving the growth of cardiac blood vessels by inserting a catheter into a coronary artery and injecting into the heart a blood vessel growth promoting peptide through an injection port of the catheter.
U.S. Pat. No. 5,419,777 is directed toward a catheter for injection of a fluid into body cavities such as coronary vessels and arteries. This patent, as is the case with the ""061 patent, illustrates the use of an injection needle which protrudes laterally through the side walls of the distal tip of the catheter. In the case of drug injections to be made into coronary vessels and arteries, it is very desirable to have the needles extend out of the side walls of the catheter and at an acute angle to the walls of the vessel in order to penetrate the walls of the vessel for injection of the agent.
U.S. Pat. No. 5,431,168, assigned to the same assignee as the present patent application, is directed toward a steerable catheter which includes a puller wire for controlling the distal end of the catheter from a control handle which is mounted on the proximal end of the catheter.
Copending U.S. patent application Ser. No. 09/019,453, entitled xe2x80x9cIntracardiac Drug Delivery,xe2x80x9d assigned to an affiliated company of the assignee of this application, discloses an injection catheter system for infusing a diagnostic or therapeutic agent into the wall of an organ which includes an electromagnetic sensor disposed within the distal tip of the catheter for providing very precise location information for the distal tip of the catheter. The subject matter of this copending patent application is incorporated by reference into the subject patent application.
This present invention is directed to a catheter for infusing therapeutic or diagnostic agents into the tissue of organs having a spring-loaded handle for controlled extension of an injection needle. In one embodiment the catheter comprises a catheter body comprising a flexible tubing having proximal and distal ends and at least one lumen therethrough. A tip section comprising a flexible tubing having proximal and distal ends is mounted at its proximal end to the distal end of the catheter body. It is understood that the tip section and catheter body can be two separate components fixedly attached together or a single integral tubing wherein the tip section is the distal end of the tubing on which is mounted, for example, the tip electrode and ring electrodes.
A needle control handle is provided at the proximal end of the catheter body, and may or may not be directly mounted to the catheter body. The needle control handle comprises an outer body and a piston. The outer body has a piston chamber in its proximal end. The distal end of the piston is slidably mounted within the piston chamber. A compression spring is provided in the piston chamber between the piston and the outer body. The compression spring can be aligned such that one end of the compression spring is in contact with the outer body, while the other end is in contact with the piston. Alternatively, one end of the compression spring can be fixed relative to the outer body, while the other end of the compression spring is fixed relative to the piston.
An injection needle extends through the tip section, catheter body, and needle control handle. The proximal end of the injection needle is attached to the piston, either directly or indirectly, and the distal end of the injection needle is contained within the distal end of the tip section when in a retracted position, e.g. when the catheter is being introduced into the patient.
Application of a distal force to the piston causes distal movement of the piston relative to the outer body, compressing the compression spring. This results in distal movement of the injection needle relative to the outer body, catheter body and tip section so that the distal end of the injection needle extends outside the distal end of the tip section. Upon removal of the distal force, the compression spring expands to exert a force on the piston, causing proximal movement of the piston relative to the outer body. This movement causes the distal end of the injection needle to retract into the distal end of the tip section.
In another embodiment the catheter comprises a catheter body and tip section as described above and a needle control handle. The needle control handle comprises an outer body having a piston chamber therein and a piston having its proximal end slidably mounted within the piston chamber. A compression spring is provided in the piston chamber between the piston and the outer body. The compression spring can be aligned such that one end of the compression spring is in contact with the outer body, while the other end is in contact with the piston. Alternatively, one end of the compression spring can be fixed relative to the outer body while the other end of the compression spring is fixed relative to the piston. An injection needle extends through the tip section, catheter body, and needle control handle. The proximal end of the injection needle is attached to the outer body, either directly or indirectly, and the distal end of the injection needle is within the distal end of the tip section when in a retracted position.
Application of a distal force to the outer body causes distal movement of the outer body relative to the piston, compressing the compression spring. This results in distal movement of the injection needle relative to the piston and catheter body so that the distal end of the injection needle extends outside the distal end of the catheter body. Upon removal of the distal force, the compression spring expands to exert a force on the outer body, causing proximal movement of the outer body relative to the piston. This movement causes the distal end of the injection needle to retract into the distal end of the tip section.
In another embodiment the catheter comprises a catheter body and tip section as described above and a needle control handle. The needle control handle comprises an outer body having a piston chamber therein and a piston having one end slidably mounted within the piston chamber. A compression spring is provided in the piston chamber between the piston and the outer body. The compression spring can be aligned such that one end of the compression spring is in contact with the outer body, while the other end is in contact with the piston. Alternatively, one end of the compression spring can be fixed relative to the piston and the other end of the compression spring is fixed relative to the piston. An injection needle extends through the tip section, catheter body, and needle control handle. The proximal end of the injection needle is attached to one of the outer body and the piston, either directly or indirectly, and the distal end of the injection needle is within the distal end of the tip section.
Application of a distal force to one of the outer body and the piston causes distal movement of the other of the outer body and the piston, thereby compressing the compression spring. This results in distal movement of the injection needle relative to the catheter body so that the distal end of the injection needle extends outside the distal end of the catheter body.